Evolution of Aspergillus fumigatus virulence

专性需氧真核病原体在感染过程中面临的一个重大挑战是 低氧微环境在氧气耗尽的情况下获得足够氧气的能力现在已经 已被证明是烟曲霉和其他真核病原菌的毒力的关键。但 知识上的主要差距是专性好氧真菌如何在面临氧气耗尽时获得氧气。的in 在低氧条件下进行的体外实验进化实验，以确定A. 烟曲霉缺氧适应性揭示了真菌菌丝体或生物膜形态的意外变化。一 真菌菌落犁沟的显著增加，即所谓的皱纹菌落形态， 进化的菌株，与亲本菌株相比，伴随着低氧适应性的增加。重要的是这 形态变化和增加的缺氧适应性与毒性强烈相关。检查一个大的 收集A。毒力和低氧适应性增加的烟曲霉菌株显示出相似的菌落 形态变化进化菌株的初步全基因组测序确定了一个突变， 新的未经研究的真菌特异性基因，我们目前称之为eefA。eefA的过度表达或缺失 影响真菌菌落形态、缺氧适应性和毒力。在本提案中，我们将检验假设 增加的菌落开沟代表了真菌获得氧气的一种新机制， 毒性。利用分子遗传学、生物化学和宿主-病原体相互作用的方法，我们将定义 eefA介导真菌氧获取和毒力的新功能。初步数据显示， 菌丝能够附着并形成沟槽，促进氧气进入真菌细胞深处， 菌丝体真菌菌落形态和结构如何影响A.烟曲霉毒力尚未研究， 代表了一种新的模式，在面对低氧应激的体内健身的机制。因此，委员会认为， 这些研究将为A.烟曲霉毒力机制，并预计 确定新的治疗方法来阻止真菌体内氧获取以改善疾病结果。

A significant challenge faced by obligate aerobic eukaryotic pathogens during infection is low oxygen microenvironments. The ability to acquire sufficient oxygen in the face of oxygen depletion has now been shown to be critical for Aspergillus fumigatus and other eukaryotic pathogen's virulence. However, a major gap in knowledge is how obligate aerobic fungi acquire oxygen in the face of oxygen depletion. An in vitro experimental evolution experiment conducted under low oxygen conditions to identify mechanisms of A. fumigatus hypoxia fitness revealed an unexpected change in the fungal mycelium, or biofilm, morphology. A substantial increase in fungal colony furrowing, a so called rugose colony morphology, was observed in the evolved strain with a concomitant increase in hypoxia fitness compared to the parental strain. Importantly, this morphological change and increased hypoxia fitness strongly correlates with virulence. Examination of a large collection of A. fumigatus strains with increased virulence and hypoxia fitness reveals similar colony morphological changes. Preliminary whole genome sequencing of the evolved strain identified a mutation in a novel unstudied fungal specific gene we currently call eefA. Over-expression or loss of eefA dramatically affects fungal colony morphology, hypoxia fitness, and virulence. In this proposal, we will test the hypothesis that increased colony furrowing represents a novel mechanism for fungal oxygen acquisition that is critical for virulence. Using molecular genetics, biochemical, and host-pathogen interaction approaches, we will define the novel function of eefA in mediating fungal oxygen acquisition and virulence. Preliminary data strongly link eefA with the ability of hyphae to adhere and form furrows that promote oxygen access to fungal cells deep within the mycelium. How fungal colony morphology and structure affects A. fumigatus virulence is unstudied and represents a new paradigm for a mechanism of in vivo fitness in the face of low oxygen stress. Consequently, the proposed studies will reveal new insights into A. fumigatus virulence mechanisms and are expected to identify novel therapeutic approaches to thwart fungal oxygen acquisition in vivo to improve disease outcomes.